The present invention relates to a method an apparatus for transporting load units, for example, containers, and more specifically relates to loading and unloading containers onto and off from larger transport vessels using a transport trolley.
From U.S. Pat. No. 5,618,148 there are known a method and an arrangement for transporting larger units, especially for loading and unloading containers, the method and system being developed to provide a loading and unloading system which is specifically fast and effective, and which particularly finds application in connection with high-speed container boats.
The present invention is a further development of a system as disclosed in U.S. Pat. No. 5,618,148, and the development is specifically concentrated upon making such loading and unloading systems even faster and more automatically operated.

From UK patent application 2 291 032 (Sxc3x8orensen/Thorny Croft Guilds and Co. Inc.) there is known an apparatus for use in transporting a load wherein a plurality of transporters are arranged as a train having a predetermind length. Preferably the prior art train is formed such that the length thereof corresponds substantially to the effective length of a selected position on a cargo deck of the vessel to be loaded.
However, according to said GB 2 291 032 there are suggested transporters comprising gaseous supporting means arranged at each corner of each transporter, which as an outset are independent of any driving rails. However, although such a gaseous support arrangement is independent of any driving rails the arrangement according to UK 2 291 032 is dependent upon guiding rails along which the transporters have to be guided when entering the transport vessel in question. Further, the traction force for the train of transporters is provided by a large locomotive which in turn requires friction contact against the surface on which the train is to be transported. On the other hand the gaseous supporting means require a smooth base, which is very difficult to provide, especially at outdoors ports.
As stated above, an object of the present invention is to provide an improvement of the system according to U.S. Pat. No. 5,618,148, by refining the technologies thereof in a new and effective manner.
Further, it is an object of the present invention to avoid the disadvantages with which the arrangement according to UK 2 291 032 are hampered, i.e. to present a method and an arrangement wherein commonly available rails can be used on deck, which rails can communicate with associated rails on shore, and wherein special transfer trolleys will be part of the port equipment for being maintained on land.
A still further object of the present invention is to provide a trolley train which comprises trolleys having their own lifting and driving equipment, as well as comprising a power trolley which can easily pass underneath the pallets or pallet loads in question, so as to drive the trolley train in any direction underneath the corresponding pallet train.
Yet another object of the present invention is to provide a unique locking system which can be operated by the trolleys themselves, so as to further increase the automatic and personal-free operation of the system.
Another object of the present invention is to provide cargo trolleys provided with means for driving in a safe and efficient manner also through curves of the associated rails.
The above objects are achieved by a method and an arrangement according to the invention, and more specifically the idea and solution as stated in the characterizing clause of the enclosed patent claim 1 and patent claim 12, respectively.